Automatic telephone system



March 24. 1925. 1,531,221

W. T. POWELL AUTOMATIC TELEPHONE S YST$M Filed Feb. 8, 1923 cs--Sheet- 1 INVENTOR WINFRED T. POWELL &9 W

. ATTO NEY w, 'r. POWELL AUTOMATIC TELEPHONE SYSTEM Filed Feb. 8, 1923 3 Sheets-Sheet 2 INVENTOR WIN FRED T. POWELL ATTORNEY FIG. 2

March 24. 1925.-

FIG.3

1,531,221 w. T. POWELL AUTOIATIC TELEPHONE SYSTEM Filesi Fe s. 1923 s Sheets-Sheet 3 INVENTOR WINFRED TPOWELL BY A W- ATTORNEY To. all whomit ine y mm.-

Patented Mar. 24, 1925.

UNITED STATES PATENT OFFICE;

WINFBED T. POWELIiQOF ROCHESTER, NEW YORK, ASSIGNOR- TO THE STROMIBERG- CARLSON TELEPH ONE'MANUFACTURI NG COMPANY, OF ROCHESTER, NEW YORK,

A CORPORATION OF NEW YORK.

Application file February Be it known that I, VINFRED T. POWELL, a citizen of the United statesyresiding at Rochester, in the county of Monroe and State of New York, have {invented certain new anduseful Improvements in Automatic 1 Telephone; Syste1ns,*of which the following is affull, clear; concise, and exac t description. i This invention relatesto. telephone. systems and more particularly to telephone 7 systems in which automaticswitchingfmeans establish some portion of a telephone connectionr 1 M In former telephone systems it has been proposed to employ relays instead of nonnumerical switches in extending calling tele phone lines to idletrunks, but such arrangements heretofore have been expensive to install and difficult to maintain inoperation because of the great number of relays-necessary to complete. the various interconnections. V

' :The present invention-has for its purpose, the reduction of the number of relays and the simplification of the circuits in which such relays are employed. 2 l i The main feature of the present inven- 7 tion resides in thelarrangeme'nt of telephone (lines in groups .and sub-groups-xand the means by which the lines of a sub-group are simultaneously extended to idle trunks on 'the initiation of a call on on'e of thelines of thesub-group.

Other features of: the invention will appear from the detailed descriptionand ap-. pended claims:

"The drawings with Figures 1,2, and 3 1 arrangedinthe order named, diagrammatia station, which are cally represent'a portion of a telephone system incorporating the present invention. At the leftof Fig. 1 there are represented two telephone lines, each provided with a sub-- designated A and .13 re-' spectively. The right hand portion of Fig. 1 and the portion of Fig. 2 at thexleft of the heavy dotted line represent agroup'of pair of linesA and B ten: interconnecting relays individual toa The verticalcolumn of relays shown just at the left of the heavy dotted line in Fig. 2are associated with, the primary group oftrunksyonexof saidrel'ays being provided for each pair of said" trunks. At the right. or the heavy dotted line in AUTOMATIC TELEPHONE SYSTEM.

8, 1923. semi No. 617,781.

3, there are represented two groups of relaysone of said groups of relays beingindividual to the even group of secondary trunks while the other of said groups of relays is individual tothe odd group of secondary trunks. At the upper right hand corner of Fig.3 and enclosed within the dotted rectangle there is indicated a numerical or connector svvitch. The disclosure of this numerical switch has been very much abbreviated, onlyits impulse relay and its first slow releasing relay being shown. It will be understood, however, that first, second and third selectors as well as the indicated connector switch may be interposed between the secondary trunks and the telephone lines. Below the dotted reotanglethere are indicated nine slow releasing relays, each one of these relays is associated witha connector switch circuit in the manner similar to that indicated. within thedotted rectangle. Although the exact grouping of the telephone lines and the primary and secondarytrunks are not essential to this invention, for purposes of this description it is assumed that the telephone lines of the system are'divided into groups of one hundred lines each and the lines of each group are arranged in subgroupsorpairs; Each group of one-hundred lines has for its. usetwenty primary trunks which are divided-into two groupsarbitrarily designated odd and even. These twenty primary trunks have access to tensecondary trunks. With such a grouping of the lines and trunks ten switching relays individual toeach pair of telephone lines serve to interconnect those lines with their twenty primary trunks. A secondary group of ten relays is provided for each primary. trunk and serves to connect this trunk with-any one of ten secondary; trunks.

Reference is made in the course of this the drawing in Powell Patent #1382012 June 21,1921, when modified by adding will best be understood by describing the method of establishing a telephone connection from a calling telephoneline such as that indicated at A to a called telephone liiie indicated at C inFig; 3.

.Vhn the subscriber" A removes his receiver froi'ii swit'ch hook, the slo'wieleasing liii'e'rclay energ" d in a aircuit ti'acea'b'le' hem grounded battery, windiug of this relay, mired-back contactand armature of the cut-off relay 6, over the upper side of the'calling' line an(l tl11 ougl1 the 'subs'tatihn A in series, ov'e'r'the lower side of the calling lihe, armaturearid back Contact ofcut oit relay 6 to grouiid. The line relay thereuponattracts its arinatur'e's to extend greunded' battery to all of the ten primary selecting i'e'lays ihdliidual. to

suine'd that the first pair of pastime-sale iiidicated inheavy lines in Figures 1', 2, and a are idle, low wouiid relay 7 iridividiial to this pair of 'tr diiks is men, so that a cit-tea closed hem grease at its inner armature and back coiitac't, conductor 8,

loii ei wiiidlii of rela 9, condhctor lfig'in nerniost front coiitaht and arnia'ture' of line relay to groun'di Relay 9 is energized inv this circ'ii'it arid extends the talking" cohdiietoi's' to tlie" calling line, through the upper ar'fniatuies and":fidiit contactsdl and 12" of 1 9; and conductor-s13 and 14- to ground-at th ef" iiiner armature and back contact relay' 15, and to grounded bat ,te'i'y through the outer back contactand ai niature'ofrelay 15 aild wiiidiiig' of relay 16. The'liiierela'y 16' is (merge; circuit and at itsaiahatures and frontconta'cts applies ground dbatter Mall of the ten mlays iiidifiuuar it the odd group or secondary trunks. Sihce it is assumed that the first secoi'idary wink of this group is idle,the slow releasing'relay 17, itid'uai to this triiiik and its n'uine'ri'cal switch, is'

in its normal condition; A circuit is therefore closed froin ground at the otitr'ariiiature and'back Contact of thisr'elay, lower windihg of switching relay 18', cofidiicthr 19 uppermost arniat'ure and Contact 20 of relay 16, xvindi'ng'of tlii'srel'ay tog'rc'iiinded battery Therelay 1 8 is thus operated connects the calling line through the c'o'nf d'iictors, 13 and 14 of the primary t-ruhlt throu'gh conductors; 21 and 22- of the selected secondary trunk circuit leading to the numerical switch indicated within the dotted rectangle.

liiiincdiatcly on the seizure otthc secthe pair of lines A and Since it is as-" onda'ry' trunk, inip'ulse rela y' 231s energized over the e'xtendedcon'nection, including the conductors of the calling line and primary and secondary trunks in series. lVith the relay 23 energized, the slow releasing relay 17 is operated in the well known manner and at its inner armature and front contact extends groiii'idover conductor 21, contact 25 and inner armature of relay 18, condiictbr 26, winding Ofthe cut-off relay 15 associated with the primary trunk and in multiple therewith, ov'erconductor' 27, cont'a'c't' 28 and armature of relay 9, left hand winding of the cut- 0H relay 6 of the calling line to-grounded battery. The low wound relay 7 is lik'e'wise energized in' multiple with the last described circuits hem grounded battery, winding of this relay cond'iit'tor 29, the upper winding, contact and armature of relay 18, contact 25, iiiner front cont'a'ct' and arr'hatur'e of relay 17 to ground. 1 a

With the relay 7 actuated, a holding c'ir cuit is close'dfor the switching relay Sir-om tuated the line relays 5 and 16 are discon nected from the calling line and from the primary t'ruhk respectively.-

When the calling line has been extended to the numerical switch" shown within the rectangle of Fig; 8 the apparatus is in condition to receive directive impulses from the dial switch at the calling station." The re mainder of theconnection is thereupon esta'blished tothe called substation C in the well knmm manner.

Let it be assumed that while the telephone line at A iscalling the telephone line at B initiates a= call; line A has served to connect the line B to the even trunk associated with the trunk to which'line'A-has been connected. The conductors 38 and 34 of the calling line have thus been connected to the conductors and- 36 of the even primary trunk but this extension of the line B to this primary trunk is ineffective until the subscriber at B initiates a'- call; At that time the conductors and 3 1 of this lineare connected inseries by the closure of the hook switch so that the line relay 37 (Fig. 3) associated with the even group of secondary trunks is energized The initiation of acall on I calling line,

conductor. 35 of. the; primary trunk, outer armature and. back contact of through its front contacts and armatures to thegroup of ten secondaryswitching relays ing the line A 17 is operated so that a circuit is now ex which are therefore in readiness to extend the selected even primary trunk to an idle secondary trunk circuit. I

i Since it has been assumedthat the first secondary trunk has been seized in extendto the called line C, the relay tended from, ground, outer armature and front contact of relay 17, armature and back I contact of .relay 39, conductor 40, upper secondary which is similar to the secondary trunk leading tojthe dotted rectangle-of Fig. 3.:

winding of relay 41, conductor 42, contacts 43 and outer armature of line relay 37 to grounded battery. The' relay 4:1 is energized in this circuit and extends. the conductors and :36 of the even primarytrunk through contacts 44 and d5 of relay 41 to a trunk which is not, shownbut The seizure of this secondary trunk is effective to actuate the slow releasing relay 39 in the manner similar to the operation of the slow releasing :relay 17. The energization of relay 39 extends ground through the ar- 1 mature and front contacts of: relays;17 and 39 to. the armature and back-contact ofrelay 46 so that the secondary trunk with which this relay is associated 'is rendered selectable. Also the operation of relay 39 is effective to holdthe relay iloperated and is effective to actuate the cut-off relay 38 which in turn disconnects the line relay 37 from its primary trunk. Also-the operation of relay 39 extends the-holding ground through the'outer armature and front contact 47 of relay 41, lower winding of this relay, connector 48, conductor 29, winding of low resistance relay 7 to grounded battery.

The switching relay ilis thus held op-- erated and this multipleenergizing path for the relay 7 maintains the relay 7 operated even after the connection between the. line A and C hasbeen disestablished. With the relay 7 thus held operated the switching relay 9 maintains the line B connected to its selected even primary trunk and this connection is maintained irrespective of whether the connection between the lines A and C is released.

At the terminationoif the 'conversationbetween A and C, the subscriber at A replaces his receiveron its switch hook, where'upon the impulse relay 23 deenergizes and shortly afterwards the slow-releasing relay 17 retracts its armatures to open the holding circuits forrelays 18 and 15 which deenergize audit the line B is not calling over a primary trunk, relay 7 switching relay 9-and cutoff relay Gare likewise deenergized to plete a.

restore the apparatus incondition to comsucceeding call. It will. be noted that as soon as a calling .line such as A has been extended to a secguard. the calling line against intrusion when it is in use.

.VVhat is claimed is 1. In an automatic telephone system, a

plurality of telephone lines arranged in groups and sub-groups, a group of primary trunks arranged in sub-groups, a group, of secondary trunks, a relay for connecting each sub-group of telephone lines to a sub group of primary trunkson the initiation of a telephone call over one of said lines sub-group, and automatically controlled means for separately extending the selected primary trunks to secondary trunks.

2. In a telephone system, a plurality of telephone lines arranged in groups'and subgroups, one line relay for each sub-group of telephone lines, a group of primary trunks arranged in sub-groups, secondary trunks, a relay for connecting each sub-group of telephone lines to a sub-group of primary trunks on the initiation of a telephone call over one of said lines ofthe sub-group, said relay being controlled by said line relay, and means for separately extending the selected primary trunks to secondary trunks.

3. In an automatic telephone system, a

groups andpairs, a group of primary trunks arranged in pairs, a group of secondary trunks, a relay for. simultaneously extending a pair of telephone lines to a pair of primary trunks and automatically controlled means for separately extending the selected pair of trunks to secondary trunks.

' 4. In an automatic telephone systei'n, a, group of telephone lines arranged in pairs, a group of primary trunks also arranged in pairs, a single switching relay actuated on the initiation of a call over either of the telephone lines of a pair to simultaneously extend said pair of telephone lines to a pair of primary trunks, means for extending the primary trunk to which the calling line is connected, means for extending the. other primary trunk ofthe pair, and means for maintaining said switching relay operated over either of said pair of primary trunks.

5. In an automatic telephone system, a plurality of telephone lines arranged in groups and sub-groups, a group of primary trunks arranged in-sub-groups, a group of secondary trunks, a relay for connecting each sub-group of telephone lines to a sub group of primary trunks on the initiation of a telephone call over one of said lines of of the ing eueh subgroup of telephone lines to a" subgroup of primary trunks on the initia tion of a telephone call over one of said lines of the sub-group, s'aidielay being controlled by said line 1-e1ay;-and're1a swit'elt in'g means for separately 7. In an automatic telephone trunks arrangedin'subroups,means for allotting primary secondary trunks, a relay for connecting a sub-group of telephonelines toe sub-'gr'oup-- of allotted primary trunks on the initiation of atelephone call over one of said telephone lines of the subgroup; and automatically controlled means the selected priinary trunks to secondary trnnk's;

8. In an automatic a" group" of primary trunks extending the seeleetc'd 'niin'ary tr nnks to' secondary trunks'.- system, a luralit of telephone lines arranged in gronps'and subgroup -a group Of primary tru'nks' for use; a group of for separately extending telephone system; a plurality of telepholie llnes', arranged in ee-met said telephone lines of the subrou and automatically controlled means for separately extendin the selected primary trunks to allotted secondary t r nnlisr 9. In an automatic tele hone system, a plurality of telephone lines arranged in airs,- 21 single line relay for each pair of telephone lines, a cut-off relay for each telephone line for disconnecting saith telephone line from its associated line relay pains of primary trunl'z's, a relay controlled by the line ielhy of a pair of telephone lines for connectin -1 said lines to a pair of primary trnnksyifieans'responsive to said connection for operating the cut-off relays of said pair of telephone lines, and means-for sepai atel'y extendin the primary trunks to secondary trunks.

10. In an automatic telephone system, a plurality of telephone lines arranged in pairs, a single line relay for each pair of telephone lines,- a cutoff relay for eaeh telephone line for disconnecting said telephone line froih 'its associated" line relay, pairs of primary trunks; a i elliy controlled by the line relay of a pair of telephone lines for connecting said lines to a pair of primary trunks, for operating the cut ofi relays of said pair of telephone lines, said means including a circuit extending through windings of said relay and said out-oil" relays, and means for separately extending the selected pi-inia y trunks to secondary trunks.

In Witness whereof, I hereunto subscribe my'nam'e this th day of February A. I). 19231 lVINFR-ED T. POWELL.

means responsive to said connection 

